There are ways of making Islamic terrorist captives talk, and tell the truth. If you can question enough people (especially captured Islamic terrorists) you can produce an intelligence bonanza even if some of them lie. How do you get information out of fanatic and suicidal terrorists? You talk to them, a lot. Forget everything you may have seen on TV about interrogating the usual suspects. There are major difference between military and criminal interrogation. Military interrogation is more like putting a jigsaw puzzle together, to get a better picture of what the enemy is up to. While a criminal interrogation is just a maze, usually involving just one suspect and all you want to do is get to a confession.
While some of the Islamic terrorist prisoners are smart and know how to keep their mouths shut most do not. How do we know this? Simple, the American military has lots of experience in this department. During World War II, intel organizations learned to deal with fanatical Japanese and Nazi German POWs. The basic trick was to pick up as many bits of information as you could and play big-time mind games on the hard cases. The important thing was to use experienced and professional interrogators to work on the resistant prisoners believed to have valuable information. A first rate interrogator is generally strictly hands off and know how to get the information using words, gestures and some pretty effective psychological techniques. Not using physical violence is a matter of professional pride. It's also another of the tricks. Most of the terrorist prisoners come from cultures where the cops and secret police usually go straight for the torture angle. Yes, torture can work, but it often kills your subjects and often scares them into giving false information. Face it, if the guy you’re working over really doesn't have anything to tell you, he'll tell you anything to stop the pain. And that will leave you with another false lead, one that you will not easily discard because you tortured it out of someone. The only time torture is really useful is when you suspect that time is critical, as when other evidence indicates a terrorist operation is about to happen and the guy you have may well know some important details. That said torture does work and that was proved time and again during World War II and later as the techniques were developed to use data already obtained to determine of a torture subject was lying. Drugs and psychological techniques were developed, particularly by the communists, to weaken subjects without physical violence. Both the Nazis and the communists also developed very effective techniques for analyzing data collected from many suspects.
Without torture you depend a lot on mind games. These are similar (but not identical) to the techniques used by a trial lawyer when cross examining a witness. Keep in mind that not all witnesses are going to tell the truth, and other don't really know what they know. So if you've seen a really good trial lawyer rip into a witness, you have an idea of what a good interrogator can do. In addition to that, the people interrogating Islamic terrorist prisoners have other advantages. As information is collected on the prisoners (from the prisoners themselves, or from other sources) the interrogators can use a form of plea bargaining to get more information. The interrogators can get in touch with the prisoners family and discuss the situation with them. Maybe an anguished telephone call or an audio or video recording from mom will help loosen tongues.
And when you are dealing with a lot of prisoners from the same organization, you can cross check data to see who's telling the truth, and who isn't. The cross checking can also clear up fuzzy memories. As you collect more information, and get inside more of the prisoners, it becomes possible to turn some of the Islamic terrorists and get them to work for you, or to insert one of your own agents into the camp to elicit more information through casual conversation. With some prisoners, you can also bargain. There are privileges that can be traded for information. Want to get in touch with the folks back home? Make it worth our while to allow that. Want to get out of here? What have you got to make that possible? Over weeks, and months, a lot can be gotten out of the prisoners about how a secretive organization like al Qaeda or ISIL (Islamic State in Iraq and the Levant) are organized, how it operates and what the objectives are. It just takes patience, and a lot of talking.